Heat dissipation for electronic tube apparatus



Nov. 9, 1948.

E. HANSEN ETAL HEAT DISSIPATION FOR ELECTRONIC TUBE APPARATUS 2 Sheets-Sheet 1 Filed June 11', 1946 GEN/aw 0' DA w:

7' 220 #ANJE INVENTOR S Nov. 9, 1948. E. HANS EIN ETAL.

' HEAT DISSIPATION FOR ELECTRONIC TUBE APEARATUS 2 Sheets-Sheet 2 Filed June 11, 1946 INVENTQR S ATTORNEY l. e v, 2, 153,4ss

HEAT DIS SIPATION? FOR'ELECTRONIC TUBE APPARATUS Edward Hansen, Queens Village, and Gerhold 0. Davis, Kew Gardens, N. Y assigngrs, by mesne assignmentsgto Jefferson StandardBroadcasting Company, a corporation oi" North Carolina Application June 11, 194 {s i iein nerssss l Thisinvention relates to electron tube systems and more especially to systems wherein a great amount of power in the form of aheat is to be dissipated from one or more of the electron tubes. A principal object of the invention is greatly to increase the power output efficiency of such devices as radio transmitters, induction heaters and the like, which employ. one or more high power electron tubes. e One of the serious if limitations in the useful sclaims. (c1. zsefzrs) power. output of such devicesas radio transmitters, is the amount of heat wattage that can be dissipated per unit time. In large power out put transmitters, it is eustomaryto employ either special air cooling, or. special watercoolingsystems, for the electron tubes which are required to handle the power output. In thevcase of air cooling, special blowers are requiredfor directa ingan air blast or stream around the tube or its associated heat. radiator.

blowers, is the fact that for any given adjust ment of the blowing systemythere is only zone maximum amount of heat that-can be safely dissipated. If the tube ontubes are subjected to sudden or accidental overloads, the air-blowing system may not be capable of supplying the necessary. cooling blast, with the result that the tube may break down. Furthermore, with-such air blowingsystems, the heat dissipation is dependentto a certain extent upontithe'iambient temperature of the air intaketo the blower, and

in dusty orhumidenvironments, special :pre cautions may have to be taken to prevent deposition of dust layers or droplets on parts of the apparatus associated with thetubei conventional method of cooling is to employ socalled water cooled tubes, the anodes of which are usually part of the tube envelope, andwhich are immersed in a water bath which is connected with a suitable water circulating system. How ever, water cooling has a number of disadvantages amongst which are; 7 e 1 c 1. Very elaborate plumbing and water supply fixtures must be employed. V

2. Special rate-of flow gauges must be provided to insure that the proper water circulation is maintained. .3. Special water control valves mustbe employed. i j

4. Unless pure water is availablefthereis dan ger of electrolysis or deterioration o fqir culating system.

5, A sudden powerov e rload on p ower out- Apart from the initial expense and themaintenance costs ofvthese The second put tubes requires a corresponding rapid change intherate of flow of the water."

".We have found that by employing a closed cooling system employing a vaporizable refriger antfit ispossible greatly to increase the useful power outputof existing electron tube equipment,

Thus for example, a radio transmitter designed to produce 50 kilowatts maximum outputwith a, Water cooling arrangement, can have its power output increased to 551 kilowattsby using the,

cooling arrangements according to this invention. i it f Accordingl y, it is another principal objector this invention to provide a system employing power outputelectron tubes, which syetem is free, from the above-noted and other disadvantages of water or air cooling arrangements.

feature of the invention r elates to an tron tu be power output arrangement having a closed cooling system which automatically fre g ulates the amount of heat dissipated in accordf ance with the power output of thetube or tubes.

Another feature relates to a I self-circulating liquid cooling system for an electron tube whereinthe heat of thetube itself determines the rate. ofcirculation of the cooling medium. l I e A further feature relates to a closed cooling systeln for electron .tubes employing a refrigerating medium which isn-orrnally in allquid phase at some predetermined temperature andwh-ose vapor pressure varies in response to a heat, ex-

change with the electron tube; the vapor pressure serving to control the rateof circulation of the refrigerant with respect to theielectron tube.

A further feature relates to a heat dissipating arrangement for electron tubes and thelike, wherein the tube, is mounted in heat exchange relation with a circulating refrigerant in a closed system, the flow of refrigerant being automatically controlled by its vapor pressure andby 1 gravity.

.A still further feature relatesto an electron tube circuit employing at least one electron tube and an associated circuitinductance in the form ofa tubular coil, the coil also serving as a conduit for a special refrigerating medium in a closed refrigeratingsystem, wherein the rate of heat dissipation is automatically controlled by the output load of theelectron tube.

A further feature relates to a novel cooli'ng ar rangement for electron tubesof the type where in the anode forms part ofthe tube envelope and whereby uniform cooling of all parts of the and the associated seal is Obtained.

A still further feature relatesto the novlor-Q allude j ganization, arrangement and relative interconnection of parts which cooperate to provide an improved electron tube cooling system.

Other features and advantages not particularly enumerated will be apparent after a consideration of the following detailed descriptions and the appended claims.

In the drawing which illustrates a preferred i application Serial No. 532,084, the coil 23 is pro- Alf-,Which can be short-circuited by suitable conembodiment,

Fig. 1 is a front elevational view ofa portion of a power amplifier and cooling system according to the invention,

Fig. 2 is a side View of Fig. 1.

Fig. 3 is a sectional viewof aportion of Figs.

l and 2.

Referring to the drawing, there are shown two electron tubes Ill, l l, which, for example, may be of the so-called external anode type, wherein the anode I2 is in the form of a cup-shaped metal member which is vacuumetight sealed to the glass bulb if Such tubes are well-known in the radio art and are generally referred to as water cooled ,tubes. Such tubes when used as high power amplifiers are required to dissipate a great I amount of heat, and it has been the usual practice to immerse the anode E2 in a water bath which in turn is connected to a watercirculating system. One of the difficulties encountered with these prior arrangements is that of insuring that the anode is kept at a uniform temperature throughout its extent, and especiallyat the sealing region with the glass l3. According to one feature of the invention, the tube is mounted so that the anode} 2 is immersed in a bath is. of brine solution or in an oil bath containing powdered graphite in suspension, or any other solutionwhose freezing point is below the lowest temperature reached by the cooling coil to be described. These baths are contained in vessels l5 which are suitably supported. within respective metalh'ousings l6 which housings are rigidly supported v oninsulator columns H on a suitable platform Knot shown) which. also supports the remainder of the equipment, preferably a liquid tight seal in the form of a suitable gasket l 8, surrounds the tube where it emerges from vessel l5.

Located within each vessel 55 isa coolingv or evaporating coil 19 of metal tubing, this coil hav- 1 ingan inside turn diameter sufficient to surround closely the anode 52-. Each coil is connected respectively to inlet and outlet pipes 20, 2i, which pass respectivelythrough the lower and upper walls ofv housing i6. Supported on the ends of the pipes 2i, for example by metal fit ings 22, is an inductance coil 23 in the form' of hollow metal tubing having two symmetrical half portions 2t, 25,- which are reversely wound with respect to each other for purposes described in detail in applicationSerial No. 532,034, filed April 21,.194e, now abandoned. The adjacent inner ends of thetwo coil sections are connected to a common bulb-like portion Zii. Bulb 26 is connected through aleng th of insulating tube 2?, such as ceramic tubing, to

a metal pipe 23 which in turn is connected to a gas manifold 29 which extends parallel to the longitudinal axis of the coil 23. Each end of the manifold isprovided with an outlet pipe 3t, 3t, which connects to the inlet of a condenser 32, 33'. Each of these condensers may be in the form of a convoluted metalpipe 3 14 (Fig, 2) having heat radiating fins 33 integrally united thereto. The outlet end of each condenser is connected by arespective metal pipe 35, 36,: to a reservoir Sheen: taininga suitable refrigerantof any well known type such as employed in household refrigerators and the like. Reservoir 3'! is connected through respective ceramic or other suitable insulator pipes 38, 39, to the inlet pipes 20 of the respective evaporator coils l9 above described, The cooling system is filled with the refrigerant to a? level;- indicated ,bl' t e. arrows 40, just slightly above the upper periphery of 'the' inductance coil 23. As described in detail in said ber f turns tobe included in the inductance coil. JFroin' the foregoing description, it will be seen that-thecoil 23 notonly serves the purpose of the usual electricaliriductance which is connected to I the tubes l0 and H as described in detail in said application Serial No. 532,084, but also it forms a part of the closed refrigerating system. As a result, the refrigerant not only serves to, maintain the anodes I2 of the electron tubes at auniform temperature, but it also serves to cool the induct ance coil 23. As a result of the heat developed at theano'des 12, the refrigerant is vaporized and causes the evolved vapor or gas to rise into the manifold 29. The pressure of the gas inthis manifold together with the force of gravity, causes the liquid refrigerant to circulate as indicated by 1 the arrows Consequently, therate cf circulation of this liquid will be a function of the gas pressure in the system which in turn will be a function of the temperature of the anodes l2. Consequent- 1y,i f these anodes rise above a certain predetermined temperature, the rate of circulation of the refrigerant will be accordingly increased, thus tending to restore the anodes to their predetermined temperatures.

While one particular embodiment has been described herein, it will be understood that various changes and modifications may be 'made without departing from the spirit and scope of the invention.

While the invention has been described in connection. with the cooling of a so-called watercooled or external anode type of tube, itwill be understood that the invention'can equally well be appliedto any other kind of high power electron tulbe such as those ordinarily referredto as air-cooled types.

What is claimed is: A

1.. Electronic tube apparatus comprising, an electron tube, .a closed refrigerating system having a cooling coil in heat exchange relation with a power output electrode of said tube, .a refrigerating liquid reservoir mounted beneath said tube, -a-.gas manifold mountedabove said tube, said reservoir, and manifold being connected to said cooling coil. H

'2, ,1 Electronic. tube apparatus comprising, a pair of ,sim.ilar electron tubes, an inductance coil in the. form of'a hollow tube, connected in, balanced relation across the output electrodes of said tubes, a reservoir for refrigerating. liquid, a pair of connections from said reservoir to thetu'bular interior of said inductance coil, each of said connections including inseries therewith a cooling coiln'rounted in heat exchange relation with one of said tubes, a common conduit forsaid refrigerating. liquid connected substantially tothe middle point of said inductance, and a pair of return conduitsconnected to said common conduit and Qat e-sa dr se v 4. A high power amplifier comprising a pair of electron tubes, a pair of tubular inductance coils reversely wound with respect to each other and having a common central connection, cooling coils connected respectively to the outer ends of each of said inductance coils, a conduit connected to said central connection between said inductance coils, a reservoir for liquid refrigerant connected to the other ends of said cooling coils, said cooling coils being mounted in heat exchange relation with respect to the output electrodes 'of said tubes, a gas manifold having a connection from its central portion to said conduit, and connections from the said reservoir to the ends of said manifold. I

5. An amplifier according to claim 4 in which the conduit connecting the central center point of said inductances tosaid manifold includes a section of insulator tubing, and the connections between said reservoir and said other ends. of said cooling coils also include a section of insulator tubing.

6. Electronic tube apparatus comprising, a reservoir for liquid refrigerant, a pair of refrigerant 6 evaporating coils connected in parallel to said reservoir, an electrical inductance coil in the form of a hollow tube, said inductance coil having its end sections connected to said reservoir through said evaporating coils, a common return conduit connected to the central section of said inductance, a gas manifold connected to the end of said conduit, and a pair of return conduits connected to the ends of said manifold and thence to said reservoir.

EDWARD HANSEN.

GERHOLD O. DAVIS.

file of this patent:

UNITED STATES PATENTS Number Name Date 854,276 Darlington May 21, 1907 1,135,103 Fortescue Apr. 13, 1915 1,371,235 Gase et al Mar. 15, 1921 1,656,826 Morrison Jan. 17, 1928 1,850,858 Weir et a1 Mar. 22, 1932 

